From Sahih Bukhari (Hadith 2706):
Narrated `Abdullah bin Ka`b bin Malik from Ka`b bin Malik:`Abdullah bin Abu Hadrad Al-Aslami owed Ka`b bin Malik some money. One day the latter met the former and demanded his right, and their voices grew very loud. The Prophet (ﷺ) passed by them and said, "O Ka`b," beckoning with his hand as if intending to say, "Deduct half the debts." So, Ka`b took half what the other owed him and remitted the other half
Reference: Bukhari 2706